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JavaScript系列（62）--实时通信系统实现详解

article 2025/2/7 12:17:46

JavaScript实时通信系统实现详解 🔄

今天，让我们深入探讨JavaScript的实时通信系统实现。实时通信是现代Web应用中不可或缺的一部分，它能够提供即时的数据交互和更好的用户体验。

WebSocket通信基础 🌟

💡 小知识：WebSocket是HTML5开始提供的一种在单个TCP连接上进行全双工通讯的协议。相比HTTP，它能够提供持久连接和双向通信能力。

// 1. WebSocket连接管理器
class WebSocketManager {
    constructor(url, options = {}) {
        this.url = url;
        this.options = {
            reconnectAttempts: 5,
            reconnectDelay: 1000,
            heartbeatInterval: 30000,
            ...options
        };
        
        this.connection = null;
        this.reconnectCount = 0;
        this.listeners = new Map();
        this.heartbeatTimer = null;
    }
    
    // 建立连接
    connect() {
        try {
            this.connection = new WebSocket(this.url);
            this.setupEventListeners();
            this.startHeartbeat();
        } catch (error) {
            this.handleConnectionError(error);
        }
    }
    
    // 设置事件监听器
    setupEventListeners() {
        this.connection.onopen = () => {
            this.reconnectCount = 0;
            this.emit('connected');
        };
        
        this.connection.onclose = () => {
            this.handleDisconnect();
        };
        
        this.connection.onerror = (error) => {
            this.handleConnectionError(error);
        };
        
        this.connection.onmessage = (event) => {
            this.handleMessage(event.data);
        };
    }
    
    // 启动心跳检测
    startHeartbeat() {
        this.heartbeatTimer = setInterval(() => {
            if (this.connection.readyState === WebSocket.OPEN) {
                this.send('heartbeat', { timestamp: Date.now() });
            }
        }, this.options.heartbeatInterval);
    }
    
    // 处理断开连接
    handleDisconnect() {
        this.stopHeartbeat();
        this.emit('disconnected');
        
        if (this.reconnectCount < this.options.reconnectAttempts) {
            setTimeout(() => {
                this.reconnectCount++;
                this.connect();
            }, this.options.reconnectDelay * this.reconnectCount);
        } else {
            this.emit('maxReconnectAttemptsReached');
        }
    }
    
    // 发送消息
    send(type, data) {
        if (this.connection.readyState !== WebSocket.OPEN) {
            throw new Error('Connection is not open');
        }
        
        const message = JSON.stringify({ type, data });
        this.connection.send(message);
    }
    
    // 停止心跳检测
    stopHeartbeat() {
        if (this.heartbeatTimer) {
            clearInterval(this.heartbeatTimer);
            this.heartbeatTimer = null;
        }
    }
}

// 2. 消息处理器
class MessageHandler {
    constructor() {
        this.handlers = new Map();
    }
    
    // 注册消息处理器
    register(type, handler) {
        if (!this.handlers.has(type)) {
            this.handlers.set(type, new Set());
        }
        this.handlers.get(type).add(handler);
    }
    
    // 处理消息
    async handle(message) {
        const { type, data } = JSON.parse(message);
        const handlers = this.handlers.get(type);
        
        if (handlers) {
            const promises = Array.from(handlers)
                .map(handler => handler(data));
            await Promise.all(promises);
        }
    }
}

// 3. 重连管理器
class ReconnectionManager {
    constructor(options = {}) {
        this.options = {
            maxAttempts: 5,
            baseDelay: 1000,
            maxDelay: 30000,
            ...options
        };
        
        this.attempts = 0;
        this.currentDelay = this.options.baseDelay;
    }
    
    // 计算下一次重连延迟
    getNextDelay() {
        const delay = Math.min(
            this.currentDelay * Math.pow(2, this.attempts),
            this.options.maxDelay
        );
        
        this.attempts++;
        return delay;
    }
    
    // 重置重连状态
    reset() {
        this.attempts = 0;
        this.currentDelay = this.options.baseDelay;
    }
    
    // 检查是否可以继续重连
    canReconnect() {
        return this.attempts < this.options.maxAttempts;
    }
}

消息队列系统 📨

// 1. 消息队列
class MessageQueue {
    constructor() {
        this.queue = [];
        this.processing = false;
        this.maxRetries = 3;
    }
    
    // 添加消息
    enqueue(message) {
        this.queue.push({
            message,
            retries: 0,
            timestamp: Date.now()
        });
        
        this.processQueue();
    }
    
    // 处理队列
    async processQueue() {
        if (this.processing || this.queue.length === 0) return;
        
        this.processing = true;
        
        while (this.queue.length > 0) {
            const item = this.queue[0];
            
            try {
                await this.processMessage(item.message);
                this.queue.shift();
            } catch (error) {
                if (item.retries < this.maxRetries) {
                    item.retries++;
                    // 移到队列末尾
                    this.queue.push(this.queue.shift());
                } else {
                    // 放入死信队列
                    this.moveToDeadLetter(item);
                    this.queue.shift();
                }
            }
        }
        
        this.processing = false;
    }
    
    // 移动到死信队列
    moveToDeadLetter(item) {
        // 实现死信队列逻辑
    }
}

// 2. 优先级队列
class PriorityMessageQueue {
    constructor() {
        this.queues = new Map();
        this.priorities = ['high', 'medium', 'low'];
    }
    
    // 添加消息
    enqueue(message, priority = 'medium') {
        if (!this.queues.has(priority)) {
            this.queues.set(priority, []);
        }
        
        this.queues.get(priority).push({
            message,
            timestamp: Date.now()
        });
    }
    
    // 获取下一个消息
    dequeue() {
        for (const priority of this.priorities) {
            const queue = this.queues.get(priority);
            if (queue && queue.length > 0) {
                return queue.shift();
            }
        }
        return null;
    }
}

// 3. 消息持久化管理器
class MessagePersistenceManager {
    constructor() {
        this.storage = new Map();
        this.initStorage();
    }
    
    // 初始化存储
    async initStorage() {
        try {
            const stored = localStorage.getItem('message_queue');
            if (stored) {
                const data = JSON.parse(stored);
                this.storage = new Map(Object.entries(data));
            }
        } catch (error) {
            console.error('Failed to initialize storage:', error);
        }
    }
    
    // 保存消息
    async persistMessage(id, message) {
        this.storage.set(id, {
            message,
            timestamp: Date.now()
        });
        
        await this.saveToStorage();
    }
    
    // 保存到存储
    async saveToStorage() {
        try {
            const data = Object.fromEntries(this.storage);
            localStorage.setItem('message_queue', 
                JSON.stringify(data));
        } catch (error) {
            console.error('Failed to save to storage:', error);
        }
    }
}

实时数据同步 🔄

// 1. 实时数据同步器
class RealtimeDataSync {
    constructor(options = {}) {
        this.options = {
            syncInterval: 1000,
            batchSize: 100,
            ...options
        };
        
        this.changes = new Map();
        this.syncTimer = null;
    }
    
    // 记录变更
    recordChange(key, value) {
        this.changes.set(key, {
            value,
            timestamp: Date.now()
        });
        
        this.scheduleSyncIfNeeded();
    }
    
    // 调度同步
    scheduleSyncIfNeeded() {
        if (!this.syncTimer && this.changes.size > 0) {
            this.syncTimer = setTimeout(() => {
                this.performSync();
            }, this.options.syncInterval);
        }
    }
    
    // 执行同步
    async performSync() {
        const batch = this.prepareSyncBatch();
        if (batch.size > 0) {
            try {
                await this.sendChanges(batch);
                this.clearSyncedChanges(batch);
            } catch (error) {
                this.handleSyncError(error);
            }
        }
        
        this.syncTimer = null;
        this.scheduleSyncIfNeeded();
    }
    
    // 准备同步批次
    prepareSyncBatch() {
        const batch = new Map();
        let count = 0;
        
        for (const [key, value] of this.changes) {
            if (count >= this.options.batchSize) break;
            batch.set(key, value);
            count++;
        }
        
        return batch;
    }
}

// 2. 冲突解决器
class ConflictResolver {
    constructor() {
        this.strategies = new Map();
        this.setupDefaultStrategies();
    }
    
    // 设置默认策略
    setupDefaultStrategies() {
        this.strategies.set('lastWriteWins', (local, remote) => {
            return local.timestamp > remote.timestamp ? local : remote;
        });
        
        this.strategies.set('merge', (local, remote) => {
            return {
                ...local,
                ...remote,
                timestamp: Math.max(local.timestamp, remote.timestamp)
            };
        });
    }
    
    // 解决冲突
    resolve(local, remote, strategy = 'lastWriteWins') {
        const resolver = this.strategies.get(strategy);
        if (!resolver) {
            throw new Error(`Unknown strategy: ${strategy}`);
        }
        
        return resolver(local, remote);
    }
}

// 3. 版本控制管理器
class VersionManager {
    constructor() {
        this.versions = new Map();
        this.history = new Map();
    }
    
    // 更新版本
    updateVersion(key, value) {
        const currentVersion = this.versions.get(key) || 0;
        const newVersion = currentVersion + 1;
        
        this.versions.set(key, newVersion);
        this.recordHistory(key, value, newVersion);
        
        return newVersion;
    }
    
    // 记录历史
    recordHistory(key, value, version) {
        if (!this.history.has(key)) {
            this.history.set(key, new Map());
        }
        
        const keyHistory = this.history.get(key);
        keyHistory.set(version, {
            value,
            timestamp: Date.now()
        });
    }
    
    // 获取特定版本
    getVersion(key, version) {
        const keyHistory = this.history.get(key);
        if (!keyHistory) return null;
        
        return keyHistory.get(version);
    }
}

性能优化策略 ⚡

// 1. 消息压缩器
class MessageCompressor {
    constructor() {
        this.compressionThreshold = 1024; // 1KB
    }
    
    // 压缩消息
    async compress(message) {
        if (typeof message !== 'string') {
            message = JSON.stringify(message);
        }
        
        if (message.length < this.compressionThreshold) {
            return message;
        }
        
        const msgBuffer = new TextEncoder().encode(message);
        const compressed = await gzip(msgBuffer);
        return compressed;
    }
    
    // 解压消息
    async decompress(data) {
        if (!(data instanceof Uint8Array)) {
            return data;
        }
        
        const decompressed = await ungzip(data);
        return new TextDecoder().decode(decompressed);
    }
}

// 2. 批处理优化器
class BatchProcessor {
    constructor(options = {}) {
        this.options = {
            maxBatchSize: 100,
            maxWaitTime: 1000,
            ...options
        };
        
        this.batch = [];
        this.timer = null;
    }
    
    // 添加项目到批处理
    add(item) {
        this.batch.push(item);
        
        if (this.batch.length >= this.options.maxBatchSize) {
            this.flush();
        } else if (!this.timer) {
            this.timer = setTimeout(() => this.flush(), 
                this.options.maxWaitTime);
        }
    }
    
    // 刷新批处理
    async flush() {
        if (this.timer) {
            clearTimeout(this.timer);
            this.timer = null;
        }
        
        if (this.batch.length === 0) return;
        
        const items = [...this.batch];
        this.batch = [];
        
        await this.processBatch(items);
    }
}

// 3. 连接池管理器
class ConnectionPool {
    constructor(options = {}) {
        this.options = {
            maxConnections: 5,
            idleTimeout: 30000,
            ...options
        };
        
        this.connections = new Set();
        this.idle = new Set();
    }
    
    // 获取连接
    async getConnection() {
        let connection;
        
        if (this.idle.size > 0) {
            connection = this.idle.values().next().value;
            this.idle.delete(connection);
        } else if (this.connections.size < this.options.maxConnections) {
            connection = await this.createConnection();
            this.connections.add(connection);
        } else {
            throw new Error('Connection pool exhausted');
        }
        
        return connection;
    }
    
    // 释放连接
    releaseConnection(connection) {
        if (this.connections.has(connection)) {
            this.idle.add(connection);
            
            setTimeout(() => {
                if (this.idle.has(connection)) {
                    this.closeConnection(connection);
                }
            }, this.options.idleTimeout);
        }
    }
}

安全性考虑 🔒

// 1. 消息加密器
class MessageEncryptor {
    constructor() {
        this.keyPair = null;
        this.initializeKeyPair();
    }
    
    // 初始化密钥对
    async initializeKeyPair() {
        this.keyPair = await window.crypto.subtle.generateKey(
            {
                name: 'RSA-OAEP',
                modulusLength: 2048,
                publicExponent: new Uint8Array([1, 0, 1]),
                hash: 'SHA-256'
            },
            true,
            ['encrypt', 'decrypt']
        );
    }
    
    // 加密消息
    async encrypt(message) {
        const encoded = new TextEncoder().encode(
            typeof message === 'string' ? message : JSON.stringify(message)
        );
        
        return window.crypto.subtle.encrypt(
            {
                name: 'RSA-OAEP'
            },
            this.keyPair.publicKey,
            encoded
        );
    }
    
    // 解密消息
    async decrypt(encrypted) {
        const decrypted = await window.crypto.subtle.decrypt(
            {
                name: 'RSA-OAEP'
            },
            this.keyPair.privateKey,
            encrypted
        );
        
        return new TextDecoder().decode(decrypted);
    }
}

// 2. 认证管理器
class AuthenticationManager {
    constructor() {
        this.tokens = new Map();
    }
    
    // 验证令牌
    async validateToken(token) {
        if (!token) return false;
        
        const tokenInfo = this.tokens.get(token);
        if (!tokenInfo) return false;
        
        if (tokenInfo.expiresAt < Date.now()) {
            this.tokens.delete(token);
            return false;
        }
        
        return true;
    }
    
    // 生成新令牌
    async generateToken(userId) {
        const token = await this.createSecureToken();
        
        this.tokens.set(token, {
            userId,
            expiresAt: Date.now() + 24 * 60 * 60 * 1000 // 24小时
        });
        
        return token;
    }
}

// 3. 速率限制器
class RateLimiter {
    constructor(options = {}) {
        this.options = {
            windowMs: 60000, // 1分钟
            maxRequests: 100,
            ...options
        };
        
        this.requests = new Map();
    }
    
    // 检查请求是否允许
    async checkLimit(clientId) {
        this.removeOldRequests(clientId);
        
        const requests = this.requests.get(clientId) || [];
        if (requests.length >= this.options.maxRequests) {
            return false;
        }
        
        requests.push(Date.now());
        this.requests.set(clientId, requests);
        return true;
    }
    
    // 移除过期请求记录
    removeOldRequests(clientId) {
        const now = Date.now();
        const windowStart = now - this.options.windowMs;
        
        const requests = this.requests.get(clientId) || [];
        const validRequests = requests.filter(time => time > windowStart);
        
        if (validRequests.length < requests.length) {
            this.requests.set(clientId, validRequests);
        }
    }
}

最佳实践建议 💡

  1. 连接管理模式
// 1. 连接状态管理器
class ConnectionStateManager {
    constructor() {
        this.state = 'disconnected';
        this.listeners = new Set();
    }
    
    // 更新状态
    setState(newState) {
        const oldState = this.state;
        this.state = newState;
        
        this.notifyListeners(oldState, newState);
    }
    
    // 添加状态监听器
    addListener(listener) {
        this.listeners.add(listener);
    }
    
    // 通知监听器
    notifyListeners(oldState, newState) {
        for (const listener of this.listeners) {
            listener(oldState, newState);
        }
    }
}

// 2. 重试策略
class RetryStrategy {
    constructor(options = {}) {
        this.options = {
            initialDelay: 1000,
            maxDelay: 30000,
            factor: 2,
            maxAttempts: 5,
            ...options
        };
    }
    
    // 计算延迟时间
    getDelay(attempt) {
        const delay = this.options.initialDelay * 
            Math.pow(this.options.factor, attempt);
            
        return Math.min(delay, this.options.maxDelay);
    }
    
    // 检查是否应该重试
    shouldRetry(attempt, error) {
        if (attempt >= this.options.maxAttempts) {
            return false;
        }
        
        // 根据错误类型决定是否重试
        return this.isRetryableError(error);
    }
}

// 3. 日志记录器
class CommunicationLogger {
    constructor() {
        this.logs = [];
        this.maxLogs = 1000;
    }
    
    // 记录日志
    log(type, data) {
        const logEntry = {
            type,
            data,
            timestamp: Date.now()
        };
        
        this.logs.push(logEntry);
        
        if (this.logs.length > this.maxLogs) {
            this.logs.shift();
        }
        
        this.persistLogs();
    }
    
    // 持久化日志
    persistLogs() {
        try {
            localStorage.setItem('communication_logs', 
                JSON.stringify(this.logs));
        } catch (error) {
            console.error('Failed to persist logs:', error);
        }
    }
}

结语 📝

实时通信系统是现代Web应用中的重要组成部分。通过本文，我们学习了：

  1. WebSocket通信的基础实现
  2. 消息队列系统的设计
  3. 实时数据同步机制
  4. 性能优化策略
  5. 安全性考虑和最佳实践

💡 学习建议：在实现实时通信系统时，要特别注意连接的可靠性和消息的可靠传递。同时，要根据实际需求选择合适的同步策略，平衡实时性和系统负载。

如果你觉得这篇文章有帮助，欢迎点赞收藏，也期待在评论区看到你的想法和建议！👇

终身学习，共同成长。

咱们下一期见

💻


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